1. Technical Field
The present invention relates to a vehicle drive device provided with a left wheel drive unit for driving a left wheel and a right wheel drive unit for driving a right wheel.
2. Description of the Related Art
In Japanese Patent No. 3138799, a vehicle drive device is described which is equipped with a left wheel drive unit having a first electric motor for driving a left wheel of a vehicle and a first planetary gear transmission provided on the power transmission path between the first electric motor and the left wheel, and also equipped with a right wheel drive unit having a second electric motor for driving a right wheel of the vehicle and a second planetary gear transmission provided on the power transmission path between the second electric motor and the right wheel. In the first and second planetary gear transmissions, the first and second electric motors are respectively connected to the sun gears thereof, the left wheel and the right wheel are respectively connected to the planetary carriers thereof, and the ring gears thereof are connected to each other. Furthermore, the vehicle drive device is provided with braking means for braking the rotation of the ring gears by releasing or engaging the connected ring gears.
In the vehicle drive device configured as described above, it is described that start assist control is performed at the time of vehicle start by engaging braking means. Furthermore, it is also described that torque control is performed so that the torques generated by the first and second electric motors have directions opposite to each other with the braking means released after the start, whereby even when a yaw moment is exerted to the vehicle due to disturbance or the like, a moment opposed to this yaw moment is generated, and the straight traveling stability and the turning stability of the vehicle are improved.
In the vehicle drive device described in Japanese Patent No. 3138799, however, nothing is described about how to control the electric power of an electric power source for supplying electric power to the first and second electric motors at the time when the yaw moment is generated. Hence, the vehicle drive device has room for improvement in electric power saving and in countermeasures for problems occurred in the electric power source.